<?php
/**
 * Zend Framework
 * LICENSE
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 * @category Zend
 * @package Zend_Form
 * @subpackage Decorator
 * @copyright Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
 * @license http://framework.zend.com/license/new-bsd New BSD License
 */
/**
 * Zend_Form_Decorator_Abstract
 */
require_once 'Zend/Form/Decorator/Abstract.php';

/**
 * Zend_Form_Decorator_Callback
 * Execute an arbitrary callback to decorate an element.
 * Callbacks should take
 * three arguments, $content, $element, and $options:
 * function mycallback($content, $element, array $options)
 * {
 * }
 * and should return a string. ($options are whatever options were provided to
 * the decorator.)
 * To specify a callback, pass a valid callback as the 'callback' option.
 * Callback results will be either appended, prepended, or replace the provided
 * content. To replace the content, specify a placement of boolean false;
 * defaults to append content.
 * @category Zend
 * @package Zend_Form
 * @subpackage Decorator
 * @copyright Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
 * @license http://framework.zend.com/license/new-bsd New BSD License
 * @version $Id: Callback.php 24593 2012-01-05 20:35:02Z matthew $
 */
class Zend_Form_Decorator_Callback extends Zend_Form_Decorator_Abstract {

    /**
     * Callback
     * @var string array
     */
    protected $_callback;

    /**
     * Set callback
     * @param callback $callback
     * @return Zend_Form_Decorator_Callback
     * @throws Zend_Form_Exception
     */
    public function setCallback ($callback) {
        if ( ! is_callable ($callback)) {
            require_once 'Zend/Form/Exception.php';
            throw new Zend_Form_Exception ('Invalid callback provided to callback decorator');
        }
        $this -> _callback = $callback;
        return $this;
    }

    /**
     * Get registered callback
     * If not previously registered, checks to see if it exists in registered
     * options.
     * @return null string array
     */
    public function getCallback () {
        if (null === $this -> _callback) {
            if (null !== ($callback = $this -> getOption ('callback'))) {
                $this -> setCallback ($callback);
                $this -> removeOption ('callback');
            }
        }
        return $this -> _callback;
    }

    /**
     * Render
     * If no callback registered, returns callback.
     * Otherwise, gets return
     * value of callback and either appends, prepends, or replaces passed in
     * content.
     * @param string $content
     * @return string
     */
    public function render ($content) {
        $callback = $this -> getCallback ();
        if (null === $callback) {
            return $content;
        }
        $placement = $this -> getPlacement ();
        $separator = $this -> getSeparator ();
        $response = call_user_func ($callback, $content, $this -> getElement (), $this -> getOptions ());
        switch ($placement) {
            case self::APPEND :
                return $content . $separator . $response;
            case self::PREPEND :
                return $response . $separator . $content;
            default :
                
                // replace content
                return $response;
        }
    }

}
